Microscopic mechanism of tunable thermal conductivity in carbon nanotube-geopolymer nanocomposites

TL;DR

This study uses molecular dynamics simulations to explore how the size, content, and distribution of carbon nanotubes influence the thermal conductivity of geopolymer nanocomposites, revealing mechanisms for tunable heat transfer properties.

Contribution

It provides a microscopic understanding of how carbon nanotubes affect thermal conductivity in geopolymer nanocomposites, offering theoretical guidance for designing materials with adjustable heat transfer.

Findings

Thermal conductivity increases by 125.6% at 16.5% CNT content in the axial direction.

Size effects significantly influence thermal properties due to CNTs.

Interfacial thermal resistance and phonon scattering reduce conductivity in some orientations.

Abstract

Geopolymer has been considered as a green and low-carbon material with great potential application due to its simple synthesis process, environmental protection, excellent mechanical properties, good chemical resistance and durability. In this work, the molecular dynamics simulation is employed to investigate the effect of the size, content and distribution of carbon nanotubes on the thermal conductivity of geopolymer nanocomposites, and the microscopic mechanism is analyzed by the phonon density of states, phonon participation ratio and spectral thermal conductivity, etc. The results show that there is a significant size effect in geopolymer nanocomposites system due to the carbon nanotubes. In addition, when the content of carbon nanotubes is 16.5%, the thermal conductivity in carbon nanotubes vertical axial direction (4.85 W/(mk)) increases 125.6% compared with the system without carbon nanotubes (2.15 W/(mk)). However, the thermal conductivity in carbon nanotubes vertical axial direction (1.25 W/(mk)) decreases 41.9%, which is mainly due to the interfacial thermal resistance and phonon scattering at the interfaces. The above results provide theoretical guidance for the tunable thermal conductivity in carbon nanotube-geopolymer nanocomposites.